In recent years, there has been proposed a next generation mobile communication system such as LTE (Long Term Evolution).
In a mobile communication system, it is assumed that a plurality of types of cells (for example, a general cell and a specific cell) having different coverage areas are coexisting. The coverage area of the general cell is larger than a coverage area of the specific cell. The general cell is, for example, a macro cell provided by a communication provider. The specific cell is, for example, is a femto cell or a home cell provided by a third party other than the communication provider. However, the specific cell may be a CSG (Closed Subscriber Group) cell or a pico cell provided by the communication provider.
Here, the coverage area of the specific cell is considered to exist within the coverage area of the general cell. In such a case, an uplink signal transmitted from a mobile terminal (hereinafter, a general mobile terminal) that is in an idle state or a connected state in the general cell is considered to give interference to the specific cell.
However, the general cell is not able to identify the general mobile terminal that gives interference to the specific cell. Therefore, even when a signal (for example, OI: Overload Indicator) indicating that interference occurs is transmitted from the specific cell to the general cell, the general cell is not able to resolve the interference given to the specific cell.